# AS Physics - Electricity

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#1
Hi

I have doing some exam questions on electricity and i came across an example where the current through an ammeter changes if the switch is closed or open. Why does this happen?
0
3 years ago
#2
(Original post by GG16)
I have doing some exam questions on electricity and i came across an example where the resistance through an ammeter changes if the switch is closed or open. Why does this happen?
Could you post it? An ideal ammeter has zero resistance.
0
3 years ago
#3
(Original post by GG16)
Hi

I have doing some exam questions on electricity and i came across an example where the resistance through an ammeter changes if the switch is closed or open. Why does this happen?
is it not because as current flows through it, resistance will increase due to heating?
0
#4
Hi I have attached it
(Original post by GG16)
Hi

I have doing some exam questions on electricity and i came across an example where the resistance through an ammeter changes if the switch is closed or open. Why does this happen?
(Original post by GG16)
Hi

I have doing some exam questions on electricity and i came across an example where the resistance through an ammeter changes if the switch is closed or open. Why does this happen?
0
3 years ago
#5
(Original post by vvlp)
is it not because as current flows through it, resistance will increase due to heating?
What I'm thinking.
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3 years ago
#6
(Original post by GG16)
Hi I have attached it
the question isn't implying the resistance in the ammeter changes, it's saying the overall resistance will change in the circuit
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3 years ago
#7
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3 years ago
#8
(Original post by MartynaJP6)
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3 years ago
#9
Im thinking the current will increase when the switch is on, as the current will choose to pass through the short circuit, and so won't be resisted by the resistor connected to the switch. Ideas?
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3 years ago
#10
(Original post by MartynaJP6)
Im thinking the current will increase when the switch is on, as the current will choose to pass through the short circuit, and so won't be resisted by the resistor connected to the switch. Ideas?
yep, i agree. could even work it out; wouldn't be hard to do.
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3 years ago
#11
V=IR!
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3 years ago
#12
(Original post by MartynaJP6)
Im thinking the current will increase when the switch is on, as the current will choose to pass through the short circuit, and so won't be resisted by the resistor connected to the switch. Ideas?
This type of stuff confuses me. Why would the current not split at the junction, and go through both parts, then when it meets up again it has he same current then at the start (kirchoffs law)
Because in a parallel circuit the current doesnt just choose to only go trough one junction, it is split between the two?
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3 years ago
#13
(Original post by Rexar)
This type of stuff confuses me. Why would the current not split at the junction, and go through both parts, then when it meets up again it has he same current then at the start (kirchoffs law)
Because in a parallel circuit the current doesnt just choose to only go trough one junction, it is split between the two?
I get you, its confusing. I've been taught that if current has the option to go through a short circuit and skip going through a component, it will do so. If there is a tiny door and a spacious door, more people will go through the spacious one; its easier.
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3 years ago
#14
Because when the switch is closed no current will flow through the first resistor it will avoid it because it now has a path where there is no resistance before the second resistor.
1
3 years ago
#15
(Original post by MartynaJP6)
I get you, its confusing. I've been taught that if current has the option to go through a short circuit and skip going through a component, it will do so. If there is a tiny door and a spacious door, more people will go through the spacious one; its easier.
Fair enough, and thanks aswell, I didnt know that and im going to be taking the exam for A2 in two weeks, im doomed
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3 years ago
#16
(Original post by Rexar)
Fair enough, and thanks aswell, I didnt know that and im going to be taking the exam for A2 in two weeks, im doomed
During the exam, when you are doing circuit analysis, it will always be good to use Kirchhoff rules to check answers for the simple circuit.

For short-circuited circuit, you will find contradicting result.
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